While various fuel containers are provided with self-closing filling valves, such valves are most frequently encountered with cigarette and cigar lighters, other than disposable lighters, which may require filling with a fuel such as butane from a vessel or tank having a nozzle which can be inserted into the filling opening. The valve is unblocked during such filling and automatically closes upon withdrawal of the nozzle and completion of the filling operation, generally under spring pressure, to prevent escape of the fuel.
Filling valves for cigarette lighters and the like are known in a variety of configurations, but generally comprise a valve body which is biased by spring pressure against a sealing surface around the filling opening. The valve body thus has one sealing surface while the filling opening is surrounded by a second annular sealing surface, the two surfaces abutting to prevent escape of the fuel. In some cases one or both of the sealing surfaces are provided with a sealing washer, ring or disk. One or the other of the sealing surfaces may also be provided with a sharp edge adapted to engage with practically line contact the opposite sealing surface. Thus a sharp-edge sealing surface may be formed around the filling opening for engagement with the valve member.
In practice it has been found that contaminants may appear on one or both of the sealing surfaces and may hold the valve partially open with the effect that the fuel escapes, especially since the foreign matter or contaminant is frequently a fibrous material which may derive from the wick which is customarily associated with the burner valve and extends into the fuel within the tank, or from the envelope, bag or other porous enclosure of an adsorption agent which can be placed in the tank in order to pick up oils or fatty substances which may be present in the fuel.